Recently, technology known as OpenFlow has been proposed (see Patent Literature 1 and Non Patent Literatures 1 and 2). In OpenFlow, communication is taken as end-to-end flow, and path control, failure recovery, load balancing, and optimization are performed on a per-flow basis. An OpenFlow switch as specified in Non Patent Literature 2 is provided with a secure channel for communication with an OpenFlow controller positioned as a control apparatus, and operates according to a flow table to which information is added and whose content is rewritten as necessary, according to an instruction from the OpenFlow controller. In the flow table, a set of the following is defined for each flow: matching rule (Header fields) against which a packet header is matched, flow statistical information (Counters), and actions (Actions) that define processing content (see FIG. 12).
For example, when a packet is received, the OpenFlow switch searches the flow table for an entry that has a matching rule (refer to the header fields in FIG. 12) conforming to header information of the received packet. If an entry conforming to the received packet is found as a result of the search, the OpenFlow switch updates the flow statistical information (Counters) and also implements processing content (packet transmission from a specified port, flooding, dropping, and the like) described in the Actions field of the entry in question, for the received packet. On the other hand, if an entry conforming to the received packet is not found as a result of the search, the OpenFlow switch forwards the received packet to the OpenFlow controller via a secure channel, requests determination of a path of the packet based on transmission source and destination of the received packet, receives a flow entry implementing this, and updates the flow table. In this way, the OpenFlow switch uses the entry stored in the flow table as a processing rule (packet handling operation) to perform packet forwarding.